Nanoscale Magnetic Materials - Magnetic Domains

Multifunctional magnetooptical sensors

Magnetooptical sensors for the measurements of magnetic fields, electrical quantities, and temperature​

MO Sensing Challenges for the applications of magnetic sensors vary greatly. In addition to the regular measurements of magnetic field quantities an important field of application of magnetic sensors is the indirect measurement of electrical quantities, in particular the electrical current. The aim of the project is to investigate multifunctional magnetooptical sensor elements that allow simultaneous optical measurements of additional functional parameters, in particular the measurement of temperatures. This will be achieved using magnetooptically active ferrimagnetic garnet layers. The read-out scheme is based on the temperature dependence of saturation magnetization and thus the corresponding variation of the magnetooptical Faraday and Voigt effect. Especially challenging is the envisioned reduction of magnetic hysteresis effects, which so far limit the overall sensitivity of the sensors. By influencing the effective pinning behavior of the domain walls, the sensitivity of the sensors will be enhanced. All studies are supported by in-operando magnetic domain observations. An essential part of the investigations is devoted to basic research on the various sensor mechanisms and the unraveling of the different signal influences for the simultaneous measurement of the respective quantities. The question of whether optical, local, and simultaneous measurements of quantities like temperature, magnetic field strength, and electric current can be detected with a single multifunctional sensor is at the center of the project. Such broadband and optical readout sensors could decisively alter measurement methods to ensure the operational safety in electrical systems. The investigation of methods for reducing the effective magnetic hysteresis by external stimuli is also of relevance for a variety of other sensor applications and thus well beyond the use of garnet layers as sensor elements.

Mulitfuctional magnetooptical sensors at DFG Gepris.

  1. N.O. Urs, B. Mozooni, P. Mazalski, M. Kustov, P. Hayes, S. Deldar, E. Quandt, J. McCord, Advanced magneto-optical microscopy: Imaging from picoseconds to centimeters - imaging spin waves and temperature distributions (invited), AIP Advances 6, 055605 (2016)
  2. M. Kustov, R. Grechishkin, M. Gusev, O. Gasanov, J. McCord,  A novel scheme of thermographic microimaging using pyro-magneto-optical indicator films, Advanced Materials 27, 5017–5022 (2015)